Things You Thought You Knew - The Ancient Planets
StarTalk Radio
Deep Dive
Why is the diameter of the sun not a straightforward measurement?
The sun's diameter is measured at its photosphere, a layer of its atmosphere where photons can escape in a straight line. However, the sun is made of plasma, which doesn't have a sharp edge. Different wavelengths of light reveal different 'edges,' complicating the measurement.
Why do we have leap days?
Leap days correct for the fact that Earth's orbit around the sun (a year) is not an exact number of days. A year is about 365.25 days, so we add a leap day every four years to account for the extra quarter day.
Why did the Gregorian calendar replace the Julian calendar?
The Julian calendar incorrectly added too many leap days, causing the calendar to drift from the solar year. The Gregorian calendar corrected this by skipping leap days in century years not divisible by 400, aligning the calendar more accurately with the Earth's orbit.
How did ancient cultures define planets?
Ancient cultures considered any celestial body that moved against the fixed stars as a planet. This included the sun, moon, Mercury, Venus, Mars, Jupiter, and Saturn.
Why are the days of the week named as they are?
The days of the week are named after ancient planets and celestial bodies. For example, Sunday is named after the sun, Monday after the moon, and so on, with each day named after a corresponding Roman or Norse deity.
- The sun's diameter varies depending on the measurement method.
- The photosphere is the layer from which visible light escapes.
- Different light spectrums reveal different 'edges' of the sun.
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